From OC, get on the 91 East. Go through Riverside and then get on the 60 East. The 60 East will join with the 10 East. Exit on the 62. You should see signs for the park on the 10 prior to the exit to the 62. Follow the 62 past the town of Yucca Valley to the Town of Joshua Tree. You will see signs for the park. I think the road is actually called Park Blvd. There are several signs. Drive down this road for about 20 minutes and you will be at the gate.